Princely Brothers and Sisters: The Sibling Bond in German Politics, 1100–1250 by Jonathan R. Lyon (review)

Jonathan Lyon’s outstanding new book turns several scholarly trends of the past several decades on their head. Taking insights about family and sibling relationships from current historical and social science literature, he applies them not to a microhistorical case study, but to the high nobility of the German empire in the twelfth and thirteenth centuries. How did relationships among brothers and sisters from nine major noble lineages determine the political development of the empire from the mid-twelfth through the mid-thirteenth centuries? Brought into conversation with questions about the sibling bond and the way families managed their influence across generations, Reichsgeschichte suddenly gets interesting again.

Kinship studies have been a staple of medieval social history for a long while now, but less attention has been paid to the family unit itself, particularly sibling relationships. An earlier generation of scholars, following the work of Karl Schmid and George Duby, tended to focus on the emergence of the agnatic lineages and primogeniture inheritance among the high medieval nobility. Lyon, however, shows that even as lordships and office holding became more narrowly circumscribed in many instances, noble families in the German kingdom continued to cultivate the fortunes of younger sons and daughters alongside their eldest sibling, with partitions of patrimony as well as offices being relatively common. What this means is that sibling groups, not merely eldest sons, were politically significant entities in medieval German politics.

The results of this approach are both surprising and compelling. Chapter 1 traces the emergence in the twelfth century of nine families that rose to prominence in the German kingdom in the wake of the Investiture Controversy: the Welfs, the Staufen, the Zähringer, the Ludowinger, the Andechs-Meraner, the Wittelsbacher, the Wettiner, the Babenberger, and the Ascanians. These are of course famous dynasties familiar to any student of German medieval history, but Lyon argues that what made them successful was the fact that they produced relatively large sibling groups whose offices, lands, and marriages together provided a critical mass of political and social capital for the family’s rise in imperial politics. Chapter 2 underscores how the continuing practice of partible inheritance ensured that even younger siblings and daughters enjoyed a certain amount of prestige and power in the next generation, providing them with the ability to assist and support other siblings in their political ambitions. Chapters 3 and 4 follow this “Baby Boom” generation, as Lyon terms it, of German nobles as they came of age in the mid-twelfth century. The most prominent figures of the period were sets of brothers: Frederick II and Conrad of Swabia (later King Conrad III); Henry the Black and Welf V of Bavaria; Henry Jasomirgott and Leopold IV of Babenberg; Conrad and Frederick of Wittelsbach.

Lyon makes a key observation when he notes that the election of Conrad III in 1138 was not so much the triumph of “Staufen” Hauspolitik over “Welfish” Hauspolitik (Conrad succeeded against the Welf candidate Henry the Proud) as it was the result of Conrad’s successful cultivation of relationships with his half-brothers in the Babenberg family, who provided crucial support for his candidacy. Conrad’s brother Frederick—the “head Staufen” of the period—played a far less significant role. A generation later, during the infamous feud between Henry the Lion (son of Henry the Proud) and Conrad’s successor (and nephew) Frederick Barbarossa, Henry found himself without the kind of sibling or kin network that earlier Welfs had been able to take advantage of. Frederick himself had only one brother, but relied on alliances with members of the other leading families, who stood to gain from the Welf’s fall, to remove Henry eventually from his offices.

The second half of the book follows the shrinking size and fortunes of these noble and royal dynasties as they entered the thirteenth century. By the mid-thirteenth century...